US20180309156A1 - Metal-ion rechargeable cell or battery - Google Patents

Metal-ion rechargeable cell or battery Download PDF

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US20180309156A1
US20180309156A1 US15/765,555 US201615765555A US2018309156A1 US 20180309156 A1 US20180309156 A1 US 20180309156A1 US 201615765555 A US201615765555 A US 201615765555A US 2018309156 A1 US2018309156 A1 US 2018309156A1
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metal
anode
liquid
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matrix
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Katherine Louise Smith
Emma Kendrick
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Sharp Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/40—Alloys based on alkali metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/137—Electrodes based on electro-active polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • One aspect of this invention relates to metal-ion cell or batteries that store electrical energy and provide electrical energy.
  • Metal-ion cells are a family of rechargeable cell types which are capable of storing and providing energy. In its most basic form a cell comprises an anode (negative electrode), a cathode (positive electrode) and an electrolyte material and this may be considered as a “cell unit”.
  • a “cell stack” consists of multiple cell units stacked vertically and/or horizontally. Multiple cell units or multiple cell stacks may be used in conjunction to form a battery.
  • Lithium-ion batteries are widely used in consumer electronic devices and are also growing in popularity in other applications such as electric vehicles.
  • Metal-ion batteries all have the same basic structure and charge and discharge via a similar reaction mechanism. For example when a lithium-ion battery is charging Li + ions deintercalate from the cathode and insert into the anode. Meanwhile charge balancing electrons pass from the cathode through the external circuit containing the charger and into the anode of the battery. During discharge the same process occurs but in the opposite direction with the external circuit able to power a load.
  • Sodium-ion batteries are analogous in many ways to the lithium-ion batteries that are in common use today, but a sodium ion Na + shuttles between the cathode and anode in place of the lithium ions Li + .
  • Lithium is not a cheap metal to source and is considered too expensive for use in large scale applications.
  • sodium-ion battery technology is still in its relative infancy but is seen as potentially advantageous; sodium is much more abundant than lithium and some researchers predict this will provide a cheaper and more durable way to store energy into the future, particularly for large scale applications such as storing energy on the electrical grid.
  • the parts of the electrode which the metal ions either intercalate into or alloy with or are held on the surface of or are held within the pores of are referred to as an active material in the battery.
  • other components may be present for example as a substrate to support the active material, as a conductive additive, to bind the electrode components together or to promote adhesion or flexibility.
  • a greater storage capacity in the active materials allows for either a smaller battery size in a device, extra energy available to the device being powered or for a greater battery life between charges.
  • the cycle life of a battery is also an important factor, with many applications demanding hundreds or in some cases thousands of cycles with only a small fraction of the initial capacity becoming unusable.
  • the main approaches which can increase the energy density of metal-ion batteries are either to develop high voltage cathode active materials or by developing high capacity anode and cathode active materials.
  • the energy density of an electrochemical cell can be specified either in Wh/Kg for the gravimetric energy density or in Wh/1 for the volumetric energy density.
  • the performance of the active materials contained in the anode or cathode can be characterised by a specific charge or discharge capacity, usually referred to just as “specific capacity”, which again may be either a specific gravimetric capacity or a specific volumetric capacity (mAh/g, mAh/cm 3 ).
  • An ideal anode active material has a high specific capacity and a low electrochemical potential. The lower electrochemical potential allows for a higher voltage available to the external circuit when the anode is placed against a cathode material within a battery cell, and the higher specific capacities allow the intercalation or alloying of more of the metal ions.
  • lithium metal is an ideal anode material for lithium ion rechargeable batteries due to its high gravimetric specific capacity (3860 mAh/g) and low negative electrochemical potential ( ⁇ 3V v standard hydrogen electrode).
  • ⁇ 3V v standard hydrogen electrode Although lithium metal anode batteries are known, there are problems in secondary cells, such as the requirement for at least a three-fold of excess of lithium, and the poor cycle life due the formation of lithium dendrites on the anode surface which also creates a safety hazard due to the risk of creating a short circuit within the battery.
  • Sodium metal anode batteries are also known, in particular the high temperature Sodium Sulfur batteries, or the ZEBRA batteries. Both of these types of batteries contain a sodium metal anode, and a sodium-beta alumina ceramic separator. They are generally operated at high temperatures of 300-350° C. because of the low conductivity of the ceramic ionic conductor. In these cases the sodium metal is a liquid, and due to the ceramic separator and surface tension of the molten sodium dendrites do not form in these systems. Some lower temperature systems have been developed wherein the anode is a mixed alkali metal eutectic. These mixed alkali metal systems form a low temperature eutectic, which means the metal mixture metal at much lower temperatures, and in some cases is a liquid at room temperature. These lower temperature sodium beta alumina type batteries have benefits due to the lower operating temperature.
  • the most popular anode for room temperature lithium-ion batteries is graphite.
  • the positive features of graphite are a flat and low working potential versus lithium, however the intercalation of lithium into graphite is limited to only one lithium ion for every six carbon atoms, 6C+Li + +e ⁇ ⁇ LiC 6 with a resulting reversible capacity of 372 mAhg ⁇ 1 .
  • the larger sodium ions cause exfoliation of the graphite anode and other forms of carbon such as hard carbon (also known as amorphous carbon) or expanded graphite oxide are often used. These materials have a specific capacity of approximately 250-300 mAhg ⁇ 1 with an average voltage of approximately 0.2V vs Na.
  • the movement of sodium ions into and out of the cathode and anode active materials should not change or damage the crystal structure. It is expected that with other anode material such as metal oxides or metal alloys, which intercalate or alloy with sodium, the specific capacity of the anode will be increased and hence the energy density of the cell.
  • nano-composites as anode materials in metal-ion batteries has also been studied, for example tin-graphite or silicon-graphite composites. Also described in the literature is the use of a carbon matrix with higher capacity anode active material particles, wherein the presence of a conductive carbon matrix can absorb the large volume changes during cycling, with an improved cycle life reported for increasing carbon content.
  • U.S. Pat. No. 6,120,933A describes a self-recharging molten salt electrochemical cell with a liquid anode.
  • U.S. Pat. No. 3,245,836 discloses a fuel cell, or regenerative molten salt battery having a positive electrode of a molten metal selected from the group consisting of lead, tin, mercury, bismuth, cadmium, gallium, and antimony, and a negative electrode of a molten metal selected from the group consisting of sodium, potassium, rubidium, lithium, calcium, and magnesium, this is typically operated at temperature greater than 500° C.
  • US2008/0044725 describes a high temperature liquid electrode battery consisting of three liquid material layers of positive electrode, electrolyte, and negative electrode, which separate according to their densities.
  • U.S. Pat. No. 8,679,621B2 discloses embedding liquid metal filled microcapsules into electrodes. In this case the liquid is not electrochemically active but designed to repair mechanical damage that occurs to a device during operation.
  • batteries can contain low temperature liquid anodes.
  • U.S. Pat. No. 8,586,227B2 proposes a sodium-beta alumina battery. This operates below 30° C. with a molten sodium eutectic anode, for example NaCs, NaK or NaRb.
  • the cathode is also a material that is in a liquid state at ambient temperature, such as a sulphur alloy (S—Br, S—I) or a low melting point ionic liquid such as FeCl 2 , NaAlCl 4 and THF (Tetrahydrofuran).
  • WO2011154869A2 proposes a sodium-air battery which includes an anode comprising molten sodium.
  • WO2011154869 proposes operating the cell at an operating temperature greater than the melting point of sodium (97.8° C.), for example between 105° C. and 110° C., to ensure the Na anode is liquid.
  • US2010/0047671A1 proposes a redox flow device in which at least one of the positive electrode or negative electrode active materials is a semi-solid (that is, is a mixture of liquid and solid phases).
  • U.S. Pat. No. 8,841,014 proposes an electrode for a lithium-ion battery that includes a liquid metal having a melting point below the operating temperature of the battery, such that the electrode that can undergo liquid-to-solid phase transformation upon lithiation as a result of the formation of high melting point intermetallics.
  • the electrode also undergoes solid-to liquid phase transformation during delithiation, returning the electrode to the initial liquid state.
  • Examples of electrodes include gallium and alloys of gallium, indium and/or tin. Materials may be mixed with the liquid metal to form an anode or to form a cathode. The aim of the design is to allow self-healing of cracks which are formed during the solid state and thereby improve the durability of the device.
  • Patent. No. 8,642,201 and US20120244418 propose a liquid metal alloy negative electrode for a lithium-ion battery.
  • the liquid metal alloy is absorbed in a porous matrix made of polymers, hydrogels or ceramics where the liquid metal alloy for the negative electrode is a liquid at the operating temperature of the device.
  • the liquid metal alloy is for example an alloy of the Sn—In—Bi—Ga system.
  • the porous matrix is not electrochemically active.
  • U.S. Pat. No. 8,658,295 proposes self-healing lithium-ion battery negative electrodes.
  • the negative electrode comprises an alloy with a melting point below 150° C., such as Sn alloyed to Bi and/or In, such that the layer can self-heal by periodically being warmed to near its melting point and therefore substantially removing any cracks in the negative electrode (but in normal operation of the battery the negative electrode is solid).
  • Lee et al Electrochemical and Solid-State Letters, 11 (3) A21-A24 (2008) discloses a liquid gallium electrode confined in a porous carbon matrix in a lithium ion battery where the gallium is a liquid during the operation of the battery with the aim of creating a self-healing anode.
  • the use of the porous carbon is to confine the Li x Ga particles at the void space to minimize their detachment.
  • Eutectic alloys have two or more components and have a eutectic composition.
  • the eutectic composition for an alloy is the composition at which all the components will melt or freeze at the same temperature and this temperature will be lower than for any other composition of the components.
  • the use of alloys of low melting temperature metals can lower the melting temperature compared with any of the pure elements. Therefore the use of eutectic alloys is useful where a low melting temperature is desirable.
  • Some low melting temperature alloys contain combinations of gallium, indium, tin, antimony, bismuth, lead, cadmium, zinc and thallium.
  • Other low melting temperature metals/alloys include Hg, CsK, NaK, NaCs and NaRb.
  • Gallium metal is quite corrosive to most other metals because of the rapidity with which it diffuses into the crystal lattices of metals. For example, only a very small amount of gallium in contact with an aluminium plate or sheet will result in immediate embrittlement as the result of the diffusion of gallium through the grain boundaries separating them.
  • the few metals that tend to resist attack by gallium are molybdenum, niobium, tantalum and tungsten (Van Nostrand's Scientific Encyclopaedia by Douglas M. Considine and Gelnn D. Considine p. 1401).
  • a first aspect of the invention provides a metal-ion electrochemical cell containing: a composite anode comprising a support matrix and electrochemically active metal droplets dispersed through the support matrix, the metal droplets having a melting point below 100° C.; a composite cathode containing an intercalation material for the metal ion; and a conducting electrolyte medium located between the anode and the cathode; wherein the metal ion consists of one or more of: sodium, zinc, magnesium, aluminium and calcium.
  • a second aspect of the invention provides a metal-ion electrochemical cell containing: an anode current collector; a composite anode comprising a support matrix and electrochemically active metal droplets dispersed through the support matrix, the metal droplets having a melting point below 100° C.; a composite cathode containing a intercalation material for the metal ion; a conducting electrolyte medium located between the anode and the cathode; and a conductive spacer layer disposed between the anode current collector and the composite anode.
  • FIG. 1 shows a metal-ion cell with a single cathode layer and a composite anode layer.
  • the composite anode layer is separated from the metallic anode current collector by a conductive spacer layer.
  • FIG. 2 shows a metal-ion cell stack with multiple cathode layers and multiple composite anode layers.
  • the composite anode layers are separated from the metallic anode current collectors by a conductive spacer layers.
  • the repeating unit to form larger stacks is also shown.
  • FIG. 3 shows a schematic of the composite anode electrode, where the supporting matrix ( 40 a ) hosts the liquid electrochemically active anode particles ( 40 b ), and the composite electrode also contains conductive additive ( 40 c ), a second electrochemically active material ( 40 d ) and a binder ( 40 e ).
  • the electrode is adhered to a conductive inter-spacer layer ( 30 ) upon an anodic current collector ( 20 ).
  • FIG. 4 shows the liquid particles ( 40 b ) surrounded by the matrix particles ( 40 a ).
  • the matrix particles ( 40 a ) may or may not completely enclose the liquid particles ( 40 b ).
  • FIG. 5 shows the matrix particles ( 40 a ) coated with the liquid particles ( 40 b ).
  • the liquid particles ( 40 b ) may or may not completely enclose the matrix particles ( 40 a ).
  • FIG. 6 shows a composite anode layer ( 40 ) with separate particles of the matrix component ( 40 a ) and liquid component ( 40 b ).
  • FIG. 7 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ).
  • FIG. 8 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally separate matrix particles ( 40 a ).
  • FIG. 9 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally separate liquid particles ( 40 b ).
  • FIG. 10 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally separate liquid particles ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 11 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ).
  • FIG. 12 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ).
  • FIG. 13 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 14 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 15 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ).
  • FIG. 16 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ).
  • FIG. 17 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 18 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 19 shows a metal-ion cell stack with multiple cathode layers and multiple composite anode layers.
  • the composite anode layers ( 40 ) are separated from the metallic anode current collectors ( 20 ) by conductive spacer layers ( 30 ).
  • the composite anode layers ( 40 ) are separated from the separator ( 50 ) by conductive spacer layers ( 45 ).
  • the repeating unit to form larger stacks is also shown.
  • FIG. 20 shows a sodium ion cell stack according to an embodiment of the present invention.
  • FIG. 21 shows EDS images showing successful incorporation of a gallium indium liquid into a carbon matrix.
  • Image (a) shows the gallium content and image (b) shows the indium content.
  • the overlap of the gallium and indium locations show the successful eutectic mixture.
  • the liquid alloy composition was Ga 0.755 In 0.245 .
  • FIG. 22 shows EDS images showing successful incorporation of a gallium indium liquid into a carbon matrix.
  • Image (a) shows the gallium content
  • image (b) shows the indium content
  • image (c) shows the tin content.
  • the overlap of the gallium, indium and tin locations show the successful eutectic mixture.
  • the liquid alloy composition was Ga 0.62 Sn 0.16 Pb 0.22 .
  • FIG. 23 shows EDS images showing successful incorporation of a gallium indium liquid into a carbon matrix.
  • Image (a) shows the indium content
  • image (b) shows the tin content
  • image (c) shows the lead content.
  • the overlap of the indium, tin and lead locations show the successful eutectic mixture.
  • the liquid alloy composition was In 0.51 Sn 0.165 Pb 0.325 .
  • an active material describes a component of either a cathode or an anode which contributes to the capacity of the electrode.
  • the cathode is the positive electrode of the cell and the anode is the negative electrode of the cell.
  • a liquid, active component refers to a component of an electrode which is electrochemically active and therefore either inserts, hosts, alloys with or mixes with the metal ions which are moving between the cathode and anode and is a liquid for at least part of an electrochemical cycle when the cell is at a temperature below 100° C.
  • One or more cells of embodiments of the invention may be incorporated into a battery.
  • particle as used herein is not intended to limit the scope of the invention and, unless specified to the contrary, may include a solid or liquid of any size or shape.
  • matrix particle refers to a non-liquid component of the composite anode which hosts the liquid component and may or may not also contribute to the capacity of the anode.
  • An embodiment of this invention relates to a reversible metal-ion cell which incorporates an electrode of one embodiment of the present invention and which may be repeatedly charged and discharged, to store energy upon charge and produce energy during the discharge.
  • the present invention is not limited to a particular cell format.
  • the battery format for embodiments of the present invention may include but is not limited to cylindrical cells, button cells, prismatic cells and pouch cells.
  • FIG. 1 the cell is shown as a pouch cell format.
  • the electrode stack is contained within a laminated pouch material ( 10 ) which prevents short circuit paths, protects the cell components from reactions with air or moisture and contains the cell components within the package.
  • the cell is comprised of an anode of an embodiment of this invention ( 40 ) and consists of at least a solid active component and a liquid active component and may in addition contain additives for binding the components together and improvement in conduction, increasing conductivity or other functions.
  • the cell also contains a cathode which incorporates a metal intercalation material ( 60 ), an ionically conducting electrolyte medium and separator ( 50 ), which is sandwiched between the anode ( 40 ) and cathode ( 60 ).
  • the anode ( 40 ) is supported by an anodic current collector ( 20 ) and the cathode ( 60 ) by a cathodic current collector ( 70 ).
  • the anodic current collector ( 20 ) may be coated with a protective layer ( 30 ).
  • the cell is placed inside a container ( 10 ), which may be laminated aluminium, which prevents short circuits and protects the cell from the air.
  • the anode and cathode are connected to an external circuit via tabs ( 80 ) which remove and input the electrons into the cell.
  • a further example is to build up a larger cell stack of to increase the capacity of the cell stack as shown in FIG. 2 where the repeating sequence required to further build up the cell stack is shown.
  • the separator ( 50 ) may be comprised of a thin film which is soaked in a liquid electrolyte.
  • the separator ( 50 ) may be comprised of a porous film, a non-woven fabric, and a woven fabric, and is made of a material of a polyolefin resin such as polyethylene and polypropylene, a fluororesin, nylon, and an aromatic aramid can be used, or in some cases cellulosic fibres or material.
  • the thickness of the separator ( 50 ) is usually about 10 to 200 ⁇ m, and preferably 10 to 30 ⁇ m.
  • the separator ( 50 ) may be a combination such that separators having differing porosities are laminated.
  • the separator ( 50 ) may additionally contain a coating of ceramic, PVDF, a surfactant chemical or any combination thereof.
  • the separator layer ( 50 ) may be a ceramic separator, this ceramic separator may for example contain ceramic particles blended with PVDF polymer or may be made by a different method.
  • the separator layer ( 50 ) may be a polymer or gel electrolyte, such as polyethylene oxide (PEO), or a block or co polymer such as polyethylene oxide-co-propylene oxide) acrylate.
  • the polymer may be plasticised with a solvent such as propylene carbonate, dimethyl sulfoxide, ethylene glycol, triethylamine, DMF (dimethylformamide), DMSO (dimethyl sulphoxide), polyethoxide ether, poly ethylene succinate, aprotic organic solvents.
  • a solvent such as propylene carbonate, dimethyl sulfoxide, ethylene glycol, triethylamine, DMF (dimethylformamide), DMSO (dimethyl sulphoxide), polyethoxide ether, poly ethylene succinate, aprotic organic solvents.
  • the separator layer ( 50 ) in some embodiments also contains a liquid electrolyte.
  • the separator layer may constitute the electrolyte—that is a gel electrolyte layer may also act as a separator.
  • the electrolyte material(s) may be any conventional or known material(s) and may comprise either aqueous electrolyte(s) or non-aqueous electrolyte(s) or mixtures thereof.
  • the electrolyte medium may include at least one of an ionic liquid.
  • solvents usable in the non-aqueous electrolyte of a sodium-ion or lithium-ion secondary battery of an embodiment of the present invention include carbonates such as propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate, ethyl methyl carbonate, isopropyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, and 1,2-di(methoxycarbonyloxy)ethane; ethers such as 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoro propyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran; esters such as methyl formate, methyl acetate, and ybutyrolactone; nitriles such as acetonit
  • a mixed solvent containing carbonates preferred is a mixed solvent of a cyclic carbonate and a non-cyclic carbonate or a mixed solvent of a cyclic carbonate and ethers.
  • These electrolyte solvents advantageously contain an alkali metal conducting salt with a weakly bound cation such as perchlorate ClO 4 ⁇ , PF 6 ⁇ , triflate (CF 3 SO 3 ) ⁇ , bis(oxalato) borate (BC 4 O 8 ⁇ , BOB) or imide/TFSI (N(SO 2 CF 3 ) 2 ).
  • Ionic liquid electrolytes may be comprised of one or more of the following salts 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-ethyl-3-methylimidazolium tetrafluoroborate; 1-butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide; 1-butyl-3-methylimidazolium tetrafluoroborate; 1-hexyl-3-methylimidazolium; bis(trifluoromethylsulfonyl)imide; 1-hexyl-3-methylimidazolium tetrafluoroborate; 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide; 1-butyl-2,3-dimethylimidazolium tetrafluoroborate; N-octylpyridinium tetrafluoroborate; N-
  • Ionic liquids included in electrolyte medium may comprise cations of the pyridine and pyrrollidinium group such as: methyl-1-propyl pyrrolidinium [MPPyrro] + , 1-methyl-1-butyl pyrrolidinium [MBPyrro] + , 1-methyl-1-propyl piperidinium [MPPip] + , 1-methyl-1-butyl piperidinium [MBPip] + , 1-methyl-1-octylpyrrolidinium [MOPyrro] + and 1-methyl-1-octylpiperidinium [MOPip] + .
  • the polymer separator film ( 50 ) may be replaced with an ionically conducting solid, glass or polymer.
  • Solid electrolytes include garnets, nasicons, lisicons, beta alumina or other alkali metal ion conducting solid oxides or sulphide glasses or solids.
  • the cathode ( 60 ) is typically comprised of a cathode active material, a conductive additive such as carbon black, carbon nanotubes, carbon fibres, tungsten carbide, and a polymeric binder such as PTFE, PVDF, CMC, EPDM, SBR, alginate, polyacrylic acid or PEO or any other appropriate polymeric binder material or mixture thereof.
  • a cathode active material such as carbon black, carbon nanotubes, carbon fibres, tungsten carbide
  • a polymeric binder such as PTFE, PVDF, CMC, EPDM, SBR, alginate, polyacrylic acid or PEO or any other appropriate polymeric binder material or mixture thereof.
  • Active material examples of the cathode ( 60 ) include layered oxides such as the lithium, sodium or mixed lithium and sodium transition metal oxides. Examples include P 2 —Na x CoO 2 , P 2 —Na 2/3 [Ni 1/3 Mn 2/3 ]O 2 , Na 0.4 MnO 2 , Na x MO 2 .
  • Sodium transition metal phosphates or sulfates such as NaFePO 4 , NaVPO 4 F, Na 3 V 2 (PO 4 ) 2 F 3 , Na 2 FePO 4 F, Na 3 V 2 (PO 4 ) 3 , Na 2 M 2 (SO 4 ) 3 , Na 2 M(SO 4 ) 2 , NaMSO 4 F and the organic cathode material P(EO) 8 NaCF 3 SO 3 (polyethylene oxide sodium trifluoromethanesulfonate), Where M is in part a redox active transition metal.
  • Lithium cathode materials include, but not exclusively lithium cobaltate, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium transition metal sulfates and sulfate fluorides (LiFeSO4F, Li 2 Fe 2 (SO 4 ) 3 ) and lithium vanadium phosphate fluoride.
  • the cathode current collector ( 70 ) is typically an aluminium foil, or carbon coated aluminium foil for lithium and sodium ion batteries. In some cases the current collector may be a carbon paper, or graphite foil.
  • the anode ( 40 ) may for example comprise any one of the materials listed in Table 1 below.
  • the anode current collector ( 20 ) is typically copper foil for lithium cells whereas aluminium can be used as well in sodium ion examples.
  • Other examples of current collector include carbon coated aluminium copper or aluminium foil or stainless steel foils. In some cases the current collector may be a carbon paper or graphite foil.
  • the conductive spacer layer ( 30 ) is not required (although may still be provided), however in the cases where the anode material is reactive with the anodic current collector the conductive spacer layer ( 30 ) is preferably provided to separate the anode material from the anode current collector.
  • the conductive spacer layer ( 30 ) may consist of a coating which has a thickness greater than 1 nm and less than 1000 micrometres. More preferably the conductive spacer layer has a thickness greater than 10 nm and less than 50 micrometres. More preferably the conductive spacer layer has thickness greater than 100 nm and less than 10 micrometres.
  • the conductive spacer layer may be formed of any material which is a solid and is electrically conductive, and forms a protective layer on the current collector.
  • the conductive spacer layer may formed from a carbon material such as carbon black, graphite, carbon nanotubes, graphene, amorphous carbon (hard carbon), other forms of carbon or any mixture of these forms of carbon.
  • the conductive spacer layer may contain a binding agent, for example but not limited to polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber, alginates, other binders or any combination thereof.
  • the conductive spacer layer ( 30 ) may be electrochemically active and so contribute to the observed capacity of the anode (although in general the spacer layer will be thin and so make only a small contribution to the overall capacity of the anode).
  • the conductive spacer layer may have a formulation similar to the matrix component of the composite anode layer ( 40 ).
  • the conductive spacer layer ( 30 ) may have a different composition to the matrix component of the composite anode layer ( 40 ), and still contribute to the observed capacity of the anode.
  • the conductive spacer layer ( 30 ) may not be electrochemically active and so may not contribute to the capacity of the anode.
  • the conductive spacer layer ( 30 ) may be formed of a material which does not react with the liquid, active component of the composite anode layer ( 40 ).
  • the conductive spacer layer ( 30 ) may be formed as a thin coating on the anodic current collector foil ( 20 ) via an elemental deposition technique.
  • This may be a chemical vapour deposition (CVD) such as metal-organic vapour phase deposition (MOCVD) or a plasma vapour deposition (PVD) or a physical vapour deposition such as thermal evaporation or electron beam evaporation or a sputter deposition technique.
  • CVD chemical vapour deposition
  • MOCVD metal-organic vapour phase deposition
  • PVD plasma vapour deposition
  • PVD physical vapour deposition
  • Examples of the protective conductive deposition layer may be metals such as W or Mo, or conductive metal oxides such as lanthanum titanate, indium tin oxide (ITO), indium gallium zirconium oxide (IGZO), or reduced TiO 2 coatings where TiO 2 is deposited and then reduced to form a conductive titanium oxide coating.
  • metals such as W or Mo
  • conductive metal oxides such as lanthanum titanate, indium tin oxide (ITO), indium gallium zirconium oxide (IGZO), or reduced TiO 2 coatings where TiO 2 is deposited and then reduced to form a conductive titanium oxide coating.
  • Example 2 Other features of Example 2 are the same as the corresponding features of Example 1.
  • the composite anode layer ( 40 ) is comprised of a supporting matrix ( 40 a ) which hosts the liquid electrochemically active anode material/particles ( 40 b ).
  • the composite anode ( 40 ) may also contain one or more of an electronically conducting additive ( 40 c ), a second electrochemically active material ( 40 d ) and a binder ( 40 e ).
  • the electrode is adhered to a conductive inter-spacer layer ( 30 ) upon an anodic current collector ( 20 ), as shown in FIG. 3 .
  • the supporting matrix ( 40 a ) is a matrix which hosts the liquid electrochemically active anode material ( 40 b ), either upon its surface, or in cavities which are integral to the matrix.
  • the supporting matrix ( 40 a ) may be comprised of an electronically conducting or an electronically insulating material.
  • the matrix ( 40 a ) may be a non-conducting matrix such as a mesoporous silica material, fumed silica, mesoporous metal oxide, zeolite (such as zeolite A or Faujisute), in this case the matrix material ( 40 a ) is also combined with a conductive additive ( 40 c ) such as carbon black, carbon nano-tubes, carbon fibres or tungsten carbide to increase the electronic conductivity of the electrode.
  • a conductive additive 40 c
  • the matrix may consist of an electronically conducting material such as carbon black, graphite, carbon nanotubes, graphene, amorphous carbon (hard carbon), mesoporous carbon foam, carbon paper, carbon fibres or other forms of carbon or any mixture of these forms of carbon.
  • an electrically conducting additive such as carbon black or carbon nano tubes may still be provided further to improve the connectivity between the particles.
  • the matrix ( 40 a ) and anodic current collector ( 20 ) may be the same component such as a metal foam such as nickel, copper or aluminium—that is, the same component may act as both anode matrix and anode current collector, and the spacer 30 may be omitted.
  • the composite anode layer may also contain a second electrochemically active anode material in addition to the liquid anode material ( 40 b ).
  • the supporting matrix ( 40 a ) comprises an electrochemically active anode material
  • the second electrochemically active anode material may be constituted by the host matrix ( 40 a ). Examples of this include a mesoporous metal oxide material, a nanoporous metal oxide, a hard carbon or amorphous carbon.
  • an electrochemically active constituent ( 40 d ) may be provided in the matrix, in addition to the liquid anode material ( 40 b ), to act as a second electrochemically active anode material.
  • the components of the anode are held together by a polymeric binder ( 40 e ) for example, but not limited to, polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber, alginates, other binders or any combination thereof.
  • the matrix ( 40 a ) includes a liquid, active component ( 40 b ).
  • the liquid, active component may consist of any metal or alloy which is a liquid below 100° C. for at least part of the electrochemical charge-discharge cycle of the cell and in addition either inserts, hosts, alloys with or mixes with the metal ions which are shuttling between the cathode and anode.
  • the liquid, active particles ( 40 b ) may be a metal or alloy with a melting point below 100° C.
  • the particles ( 40 b ) may include at least one of gallium, indium, tin, antimony, bismuth, lead, cadmium, zinc and thallium. Particularly preferred compositions are shown in Table 1.
  • a preferred composition is an alloy containing at least gallium.
  • a further preferred composition is an alloy containing at least gallium and indium and tin—for example Ga 0.685 In 0.215 Sn 0.1 has a melting point of 11° C.
  • the liquid particles ( 40 b ) may alternatively consist of other low melting temperature metals or alloys.
  • the melting points of some other metals with a melting point below 100° C. are: Hg with a melting point of ⁇ 39° C., Na with melting point 98° C., K with melting point 64° C., Rb with melting point 39° C. and Cs with melting point 28° C. Alloys of these metals may further lower the melting point.
  • some of the binary eutectic combinations are Na 31 K 69 with a melting point of ⁇ 13° C., Na 18 Rb 82 with a melting point of ⁇ 4° C. and Na 20 Cs 80 with a melting point of ⁇ 32° C. Combinations with more than two elements may lower the melting point even further.
  • Example 3 Other features of Example 3 are the same as the corresponding features of Example 1.
  • FIGS. 4-18 and 20 illustrate various possible structures for the composite anode layer of an electrode according to an embodiment of the invention, showing the liquid, anodic, active material particles ( 40 b ) and the matrix particles ( 40 a ).
  • the composite anode layer ( 40 ) in FIGS. 4-18 and 20 it should be assumed that they may also contain at least a conductive additive ( 40 c ) and a binder ( 40 e ) although for clarity they are not included in the drawings.
  • the composite anode layer ( 40 ) may also include other additives, for example as described above.
  • the liquid, anodic, active material particles ( 40 b ) may be surrounded by the matrix particles ( 40 a ).
  • the matrix particles ( 40 a ) may or may not completely enclose the liquid particles ( 40 b ) as shown in FIG. 4 .
  • the liquid particles ( 40 b ) may coat the matrix particles ( 40 a ).
  • the liquid particles ( 40 b ) may or may not completely enclose the matrix particles ( 40 a ) as shown in FIG. 5 .
  • the liquid particles ( 40 b ) and the matrix particles ( 40 a ) may form separate particles within the composite anode layer ( 40 ).
  • the composite anode layer ( 40 ) may contain any combination of separate and coated particles as shown in FIG. 6 to FIG. 18 .
  • the matrix particles ( 40 a ) may contain a functional coating to modify the surface properties and change the wetting properties of the liquid particles ( 40 b ).
  • the matrix particles ( 40 a ) may also be joined into a larger structure to create a mesoporous or macroporous structure in contact with or containing the liquid particles ( 40 b ).
  • FIG. 6 shows a composite anode layer ( 40 ) with separate particles of the matrix component ( 40 a ) and liquid component ( 40 b ).
  • FIG. 7 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ).
  • FIG. 8 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally separate matrix particles ( 40 a ).
  • FIG. 9 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally separate liquid particles ( 40 b ).
  • FIG. 10 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally separate liquid particles ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 11 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ).
  • FIG. 12 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ).
  • FIG. 13 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 14 shows a composite anode layer ( 40 ) with the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 15 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ).
  • FIG. 16 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ).
  • FIG. 17 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • FIG. 18 shows a composite anode layer ( 40 ) with the liquid particles ( 40 b ) coated with the matrix component ( 40 a ) and additionally the matrix particles ( 40 a ) coated with the liquid component ( 40 b ) and additionally separate liquid particles ( 40 b ) and additionally separate matrix particles ( 40 a ).
  • a battery containing a composite anode layer ( 40 ) is operated within the temperature range 0° C. to 100° C.
  • a preferred temperature range is between 10° C. and 45° C.
  • a more preferred temperature is the ambient temperature of the environment in which the battery is being used.
  • the battery may be heated to ensure that the liquid component ( 40 b ) is a liquid for least part of a charge-discharge cycle of the battery.
  • the heating of the battery may be continuous or the heating may be for a part of a cycle.
  • the heating of the battery may take place only for some of the cycles or for part of some of the charge-discharge cycles of the battery.
  • the liquid, active particles ( 40 b ) may be formed by any suitable method.
  • a spray coating technique may be used to form the electrode where the liquid metal or metal alloy ( 40 b ) is sprayed onto the anode current collector ( 20 ) in conjunction with or alternating with a spray consisting of the matrix material ( 40 a ) and any other components of the electrode layer including suitable solvents to make a slurry.
  • This may or may not be an electrospray.
  • This may or may not be a flame spray pyrolysis technique.
  • the metal or metal alloy ( 40 b ) may be electrodeposited onto the matrix material ( 40 a ).
  • the metal or metal alloy particles ( 40 b ) may be in a powder form and mixed with a slurry of the matrix material ( 40 a ) and other components at a temperature at which the metal or metal alloy ( 40 b ) is a solid.
  • This mixing may be carried out by any suitable mixing method, including but not limited to ball milling, ultrasonic mixing, planetary mixing, centrifugal mixing, dispersion mixing or pulverising. This slurry may then be coated onto the anode current collector ( 20 ).
  • the metal or metal alloy particles ( 40 b ) may be either a liquid or a solid and in a dispersion and mixed with a slurry of the matrix material ( 40 a ). This mixing method may include a sonication process.
  • the metal or metal alloy particles ( 40 b ) may be in a pure liquid form and be mixed with a slurry of the matrix material ( 40 a ). This mixing method may include a sonication process.
  • the metal or metal alloy particles ( 40 b ) may be either a liquid or a solid and have a functional coating in the dispersion.
  • the metal or metal alloy particles ( 40 b ) may be a homogenous composition or may consist of a core-shell structure.
  • the metal or metal alloy particles ( 40 b ) with a matrix coating ( 40 a ) may be synthesised directly in this form, for example from an oxide of the metals with a carbon coating and subsequent carbothermal reduction.
  • At least 1% of the capacity of the composite anode ( 40 ) is provided by an electrochemically active matrix material ( 40 a ). In a preferred embodiment of the present invention at least 20% of the capacity of the composite anode ( 40 ) is provided by the matrix material ( 40 a ). In a preferred embodiment the distance between the metal or metal alloy particles ( 40 b ) is sufficient that, substantially, particles ( 40 b ) in a liquid state do not make contact with other particles ( 40 b ) also in a liquid state.
  • An additional conductive spacer layer ( 45 ) may also be included in the cell between the composite anode layer ( 40 ) and the separator layer ( 50 ) as shown in FIG. 19 . It is thought that this layer may provide a benefit to the cell by preventing the liquid component ( 40 b ) of the composite anode layer ( 40 ) from blocking the pores of the separator layer ( 50 ).
  • the spacer layer ( 45 ) may consist of a coating which has a thickness greater than 1 nm and less than 1000 um. More preferably the spacer layer ( 45 ) has a thickness greater than 10 nm and less than 50 um. More preferably the spacer layer ( 45 ) has thickness greater than 100 nm and less than 10 um.
  • the spacer layer ( 45 ) may be formed of any material which is non-metal, is a solid.
  • the spacer layer ( 45 ) may formed from a carbon material such as carbon black, graphite, carbon nanotubes, graphene, amorphous carbon (hard carbon), other forms of carbon or any mixture of these forms of carbon.
  • the spacer layer ( 45 ) may contain a binding agent, for example but not limited to PTFE (Polytetrafluoroethylene), PVDF (polyvinylidene difluoride), CMC (Carboxymethyl cellulose), EPDM (ethylene propylene diene monomer), SBR (Styrene-butadiene), alginate, polyacrylic acid or PEO (polyethylene oxide), other binders or any combination thereof.
  • the spacer layer ( 45 ) may form an active part of the anode and contribute to the capacity of the anode.
  • the spacer layer ( 45 ) may have a formulation similar to the matrix component ( 40 a ) of the composite anode layer ( 40 ).
  • the spacer layer ( 45 ) may have a different composition to the matrix component ( 40 a ) of the composite anode layer ( 40 ).
  • the spacer layer ( 45 ) may not form an active part of the anode and may not contribute to the capacity of the anode.
  • the spacer layer ( 45 ) may be applied by any appropriate method after the composite anode layer ( 40 ).
  • the composite anode layer ( 40 ) has dried before the application of the spacer layer ( 45 ). Suitable application methods include but are not limited to a spray coating, drawdown, comma bar and slot die coating.
  • An exemplary cell containing an embodiment of the present invention is a sodium ion cell as shown in FIG. 20 , with a composite anode formed from a hard carbon matrix ( 40 a ) and an alloy ( 40 b ) of 10% tin, 21.5% indium and 68.5% gallium.
  • the alloy Ga 0.685 In 0.215 Sn 0.1 has a melting point of 11° C.
  • the cathode coatings ( 60 ) are formed by mixing nickel based sodium layered oxide material with small quantities of a carbon black conductive additive and a PVDF/CTFE (Chlorotrifluoroethylene) copolymer binder with NMP (N-Methyl-2-pyrrolidone) solvent. This slurry is cast onto an aluminium foil cathode current collector ( 70 ) and dried. These electrodes are then vacuum dried, cut and calendared before use in the cells.
  • the conductive carbon additive is C65 from TimCal. The ratio of the components is 87% active material, 6% binder and 5% conductive additive.
  • a hard carbon ( 40 a ) is mixed with NMP, PVDF binder ( 40 c ) and a carbon black conductive additive ( 40 e ) in a planetary centrifugal mixer.
  • the ratio of the components is 90% hard carbon 5% binder and 5% conductive additive.
  • the matrix material ( 40 a ) in this case is electrochemically active, and the matrix material ( 40 a ), conductive additive ( 40 e ) and polymeric binder ( 40 c ) provide a support for the liquid anode material ( 40 b ). This slurry is heated to 40° C.
  • the conductive carbon spacer layer ( 30 ) is electrochemically active but, for a normal thickness of the spacer layer, the spacer layer may not make a significant contribution to the overall capacity of the anode.
  • the coatings are then cut and vacuum dried before being assembled into cells. The coatings may be calendared before use to reduce the porosity.
  • the cells stacks are formed by z-folding a polypropylene separator material ( 50 ) between the layers.
  • the cathode current collector layers ( 70 ) are welded together ultrasonically with tabbing material, the anode current collector layers ( 20 ) are similarly welded together ultrasonically with tabbing material.
  • This stack is placed in a formed pouch of laminated aluminium ( 10 ).
  • An electrolyte consisting of a 1M solution of NaPF 6 in an organic solvent mix of EC:DEC (ethylene carbonate and diethyl carbonate) is added to the cell which is subsequently vacuum sealed.
  • the resultant cell is operated at temperatures above 11° C., for example at “room temperature” (20-30° C.), the Ga 0.685 In 0.215 Sn 0.1 forms the liquid active component ( 40 b ) of the anode.
  • the metal ions which originate in the cathode layer ( 60 ) and the electrolyte may be any suitable metal ion including but not limited to Li, Na, Zn, Mg, Al and Ca. In a preferred embodiment the metal ion is lithium. In another preferred embodiment the metal ion is sodium.
  • FIGS. 21-23 showing successful synthesis of three different liquid metal alloy compositions in a carbon matrix.
  • Precursors of sodium alginate were dissolved in water with of tin chloride, gallium acetyl acetate, indium acetate and lead acetate in the correct ratios for the final desired liquid metal alloy.
  • the water is driven off and sodium chloride and an amorphous powder are formed as intermediate products.
  • This mixture is fired above 700° C. under an inert atmosphere to form a metal/carbon composite and sodium chloride.
  • This mixture is then washed in a solvent to remove the sodium chloride leaving behind the desired metal alloy particles embedded in a porous carbon matrix. This method is described in more detail in U.S. Ser.
  • One aspect of the present invention describes the use of a liquid component in the anode layer of a metal ion cells with, in some cases, an additional protective and conductive layer between the composite layer containing the liquid component and the current collector.
  • the liquid component consists of a low melting point metal or metal alloy that is liquid for at least some parts of the cell operating cycle and is included in the anode layer in addition to a second electrochemically active component which is a solid at the operating temperature of the battery, and in some cases a conductive additive.
  • a metallic current collector in the metal ion battery may be protected from reacting with the liquid component of the anode by the use of a thin conductive layer which does not contain a liquid component adjacent to the current collector.
  • the presence of the liquid metal component may increase the capacity of the anode layer compared with the capacity of the second electrochemically active component alone.
  • the liquid nature of the liquid component prevents cracks forming in the metal or metal alloy. Cracks are known to form in metal or metal alloy particles during cycling due to the volume expansion with increasing metal-ion content and this may reduce the capacity of the electrode due to loss of electrical contact.
  • the metal or metal alloy only needs to be a liquid for a part of the cycle for this benefit to be realised and therefore may undergo liquid to solid and solid to liquid transitions during a charge-discharge cycle while still maintaining the benefit of one aspect of the present invention.
  • the presence of a conductive layer between the composite anode layer containing the liquid component and a metallic current collector prevents degradation of the current collector due to reactions with the liquid metal or metal alloy.
  • Gallium in particular is quite corrosive and the metals which are resistant to attack are not well suited to use as a current collector due to considerations such as cost and ductility.
  • the use of small particles for the metal or metal alloy particles provides space for volume expansion which may occur as the metal ion content in the anode is increased when the device is charged.
  • the higher surface area of the small particles compared with a bulk film may additionally help with the rate capability of the battery cell as the maximum distance for any metal ion to travel through the bulk of the metal or metal alloy to reach the surface is reduced.
  • a first aspect of the invention provides a metal-ion electrochemical cell containing a composite anode comprising a support matrix and electrochemically active metal droplets dispersed through the support matrix, the metal droplets having a melting point below 100° C.; a composite cathode containing an intercalation material for the metal ion; and a conducting electrolyte medium located between the anode and the cathode.
  • the metal ion consists of one or more of: sodium, zinc, magnesium, aluminium and calcium.
  • anode comprising a metal having a melting point below 100° C. ensure that the metal is liquid, over at least part of the charge-discharge cycle of the cell, at operating temperatures lower than this.
  • One aspect of the invention thus provides a cell that obtains the benefits associated with a liquid metal anode component (such as high specific capacity and good reversibility) without needing to be operated at high temperatures.
  • the reference to the metal being liquid “over at least part of the charge-discharge cycle of the cell” acknowledges that the metal anode material may possibly be incorporated into a solid material at some states of the charge-discharge cycle of the cell)
  • the cell may further comprise: an anode current collector; and a conductive spacer layer disposed between the anode current collector and the composite anode.
  • a second aspect of the invention provides a metal-ion electrochemical cell containing: an anode current collector; a composite anode comprising a support matrix and electrochemically active metal droplets dispersed through the support matrix, the metal having a melting point below 100° C.; a composite cathode containing a intercalation material for the metal ion; a conducting electrolyte medium located between the anode and the cathode; and a conductive spacer layer disposed between the anode current collector and the composite anode.
  • the metal ion may consist of one or more of: lithium, sodium, zinc, magnesium, aluminium and calcium.
  • the metal droplets may have a melting point of 50° C. or lower, or may have a melting point of 40° C. or lower. This allows the cell to be operated at lower temperatures. More preferably, in a cell of the first or second aspect the metal droplets may have a melting point of 20° C. or lower, as this allows the cell to be operated at operating temperatures in the range from 20° C. to 30° C. (generally regarded as “room temperature”). Further, in a cell of the first or second aspect the metal droplets may have a melting point of 0° C. or lower, or may even have a melting point as low as ⁇ 40° C., for example where the cell is intended to be used in a lowtemperature environment.
  • the conductive spacer layer between the composite anode and the anode current collector may an active part of the anode.
  • the conductive spacer layer may be formed of essentially the same material as the support matrix of the composite anode.
  • a cell of the first or second aspect may comprise a separator layer between the composite anode and the composite cathode.
  • the conducting electrolyte medium may contained in the separator layer.
  • a cell of the first or second aspect may comprise a second spacer layer between the composite anode and the separator layer.
  • the composite anode may further comprise a second electrochemically active anode material.
  • One aspect of the invention may be applied to a cell that contains single anode and a single cathode (forming a cell unit), or it may be applied to a cell stack that consist of multiple cell units. It may also be applied to a cell unit or cell stack that is incorporated into a battery.
  • One aspect of the invention relates to an improvement in metal-ion battery technology and may be applied for use in many different applications such as energy storage devices, rechargeable batteries and electrochemical devices.
  • Advantageously the cells according to an embodiment of the invention increase the capacity of the anode.

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  • Electrochemistry (AREA)
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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)
US15/765,555 2015-10-30 2016-10-28 Metal-ion rechargeable cell or battery Abandoned US20180309156A1 (en)

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GB1519253.7 2015-10-30
GB1519253.7A GB2543836A (en) 2015-10-30 2015-10-30 Metal-ion rechargeable cell or battery
PCT/JP2016/004751 WO2017073075A1 (fr) 2015-10-30 2016-10-28 Pile ou batterie rechargeable métal-ion

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US11450889B2 (en) * 2019-01-30 2022-09-20 The Board Of Trustees Of The Leland Stanford Junior University High-energy density redox-active eutectic liquid

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CN114792793B (zh) * 2021-01-25 2024-01-26 中国科学院物理研究所 一种钠离子电池添加剂和高功率钠离子电池
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US11450889B2 (en) * 2019-01-30 2022-09-20 The Board Of Trustees Of The Leland Stanford Junior University High-energy density redox-active eutectic liquid
CN112563479A (zh) * 2020-12-10 2021-03-26 香港理工大学 一种水凝胶赋形的锌负极材料及其制备方法、负极和电池

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